Sounds like you might have unzipped the wordpress package directly into your web root.
Move everything in the /wordpress/ folder to the / folder (web root) and you should be good.
If you intend to have the installation run out of the /wordpress/ directory, then update your .htaccess file to look like this:
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /wordpress/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /wordpress/index.php [L]
</IfModule>
# END WordPress